1. Field of the Invention
The invention relates in general to a method for reproducing colored masters in printing process using color reduction.
2. Description of the Prior Art
In the printing technology, printing in other words, with four inks is usually employed in the reproduction of colored masters, in other words, for color separation for the printing inks, yellow magenta, cyan and black. If one had an ideal printing process and ideal inks and ideal printing materials, it would be possible to use only three inks having colors yellow, magenta, and cyan so as to print the color black. In practice, however, lower contrast reproductions result in three color printing specially when wet-on-wet printing is utilized. For this reason, generally four-color printing are utilized using the additional fourth black color separation whereby a so-called color reduction or removal can be carried out for the other printing inks. In practice, this method is referred to as "UCR" which means "Under Color Removal". The reproduction-technical interrelationships as well as the method of obtaining color removal are described in the following articles. Kodak, Die Reproduktion, Zeitschrift fur den ReproFachmann, Vol. 13, Kodak AG, Stuttgart-Wangen, Printed in Germany, MA 5584-0869-G, Pages 14-26. This Kodak reference corresponds to Chapter 11, page 282-305 Four-Color Printing and the Black Printer of the book, Principles of Color Reproduction, J. A. C. Yule, Kodak Research Laboratories Rechester, N.Y., John Wiley & Sons, Inc. New York, London, Sydney. Reprint from the Polygraph-Jahrbuch 1967, published at Frankfurt/Main, Article "Farbrucknahme auf elektronischem Wege" by Eberhard Hennig.
Since less printing ink needs to be printed with color reduction, advantages are obtained in wet-on-wet printing and the ink consumption is lower than without color reduction. Additional advantages of color reduction are higher gray balance, printing stability and better edge sharpness because neutral transitions are then essentially printed only with the black. Printing ink in contrast to printing without color reduction errors which occur when the prints of the color separation are out of register thus have less of an effect on the sharpness impression. Since less color need to be printed in chromatic inks reduction advantages are obtained in wet-on-wet printing and the ink consumption is lower.